The field erection of straight tube heat exchangers, for example tubular air heaters containing many thousands of tubes, involves inserting the tubes in tube holes of tube sheets which are in parallel, spaced relationship, locating the tubes in the tube sheets to provide equal tube extensions from each tube sheet and welding or expanding the tubes to the tube sheets. In these operations it is necessary to provide a type of stop or locator on one end of the tubes to maintain equal tube extensions or protrusions from the tube sheets prior to welding or expanding. This is particularly important during the erection of heat exchangers with vertical tubes where it is possible that the tubes could pass completely through the tube sheets if these stops or locators were not provided. One method of providing this restraint is to flare one end of the tubes to a diameter greater than the tube hole. This is usually done at the tube manufacturing plant. Another method is to hand punch in the field one end of the tubes, forming dimples or extensions of the tube diameter to locate the tubes in the tube sheets and prevent passage through the tube sheets prior to welding or expanding. Flaring the tube ends is expensive and creates handling and shipping problems to the tube manufacturer. Straight tubes of equal outside diameters are usually bundled in a hexagonal shaped package for compactness and strapped for shipment. Obviously, a bundle of tubes with flared ends would be larged in diameter than a conventional bundle and the tapered configuration would make strapping or banding of the bundle unreliable and unsafe. It may, however, be possible to safely package tubes with flared ends using spacers of suitable design but this would be expensive and present handling problems in the manufacturing plant and at the job site. Alternating the tube ends is possible but this would only ease and not solve the handling and packaging problem. Hand punching the tubes at the job site is expensive and inaccurate and complicates erection problems.